diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index 8658b68..9d18c65 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -459,6 +459,20 @@
       Diag(AtLoc, diag::warn_property_attr_mismatch);
       Diag(PIDecl->getLocation(), diag::note_property_declare);
     }
+    else if (getLangOpts().ObjCAutoRefCount) {
+      QualType PrimaryPropertyQT =
+        Context.getCanonicalType(PIDecl->getType()).getUnqualifiedType();
+      if (isa<ObjCObjectPointerType>(PrimaryPropertyQT)) {
+        Qualifiers::ObjCLifetime PrimaryPropertyLifeTime =
+          PrimaryPropertyQT.getObjCLifetime();
+        if (PrimaryPropertyLifeTime == Qualifiers::OCL_None &&
+            (Attributes & ObjCDeclSpec::DQ_PR_weak)) {
+              Diag(AtLoc, diag::warn_property_implicitly_mismatched);
+              Diag(PIDecl->getLocation(), diag::note_property_declare);
+            }
+        }
+    }
+    
     DeclContext *DC = cast<DeclContext>(CCPrimary);
     if (!ObjCPropertyDecl::findPropertyDecl(DC,
                                  PIDecl->getDeclName().getAsIdentifierInfo())) {